It was 20 years ago this month that both parts of Tony Kushner’s theatrical masterwork “Angels in America” were first performed together, at the Mark Taper Forum in Los Angeles.

The sweeping saga, set amid the AIDS epidemic of the 1980s, hasn’t lost its power since then, as demonstrated by Ion Theatre’s stunning production in San Diego last year. Nor has time eroded the Pulitzer Prize-winning work’s ability both to provoke and inspire.

In that last category, consider “when last we flew,” the Harrison David Rivers play now getting its West Coast premiere at Diversionary Theatre. Not only is Rivers’ central character obsessed with “Angels,” but the play incorporates lines, images and variations of characters from the original.

If such a dramatic expression of devotion is going to go beyond homage, it really needs to argue for a fresh way of thinking about the original. While “when last we flew” has its moments of surprise, humor and insight as a coming-of-age story, the work doesn’t quite feel as though it crosses that “threshold of revelation” (to quote from Rivers, quoting from Kushner).

What this production does have are some worthy performances that make the most of Rivers’ more lyrical passages, and of the obvious passion the playwright has invested in the project.

The central figure (and sometime narrator) of the story is Paul, played with an appealing sensitivity by Cordell Mosteller). He’s a closeted African-American teen-ager grappling with self-doubt and family trauma in small-town Kansas.

But there’s a structural quirk at work here, because the character of the socially conscious renegade Natalie often comes off as more compelling — and, at Diversionary, benefits immensely from a fiery performance by the excellent Rory Lipede. (She’s the sole member of this cast to have also appeared in the play’s original production, at the New York Fringe Festival in 2010; director Colette Robert likewise has returned.)

Natalie has parent issues of her own: Her mom, Priscilla (Faeren Adams), comes off as ice-cold, demanding and almost devoid of sympathy.

Paul spends much of his time locked in the bathroom, reading his copy of “Angels” (pilfered from the school library) and doing his best to avoid the realities just outside the door. His mother, Marian (Lynaé DePriest), tries to cajole him to rejoin life and stop stewing over the sudden departure of his father (who appears later as one of several characters played by the versatile Marshall Anderson).

Classmate Ian (Noah Longton), who carries a torch for Paul, is his only real lifeline to the outside world. That is, until Natalie — whose tirade against racial injustice has gotten her booted from Catholic school — literally drops into Paul’s life, crashing through the ceiling like the Angel in Kushner’s work.

Rivers’ play actually has its own more direct parallel to the Angel: a mystery character (portrayed by the wry and entertaining DeAnna Driscoll) who pops up in multiple guises. Her ministrations, and the growing bond among Paul, Natalie and school newcomer Fresh (Anderson again), point everyone to a greater self-acceptance.

Matt Scott’s set has elements of visual poetry — quite literally, in the case of text fragments scrawled on walls and a blackboard. And Luke Olson’s lighting and Blair Robert Nelson’s sound contribute a feel of real mystery.

Those factors, and bursts of strong acting, help make the show move. Something else needs to make it really fly.